1. Field of the Invention
The present invention relates to an IP terminal apparatus, particularly to an IP terminal apparatus that utilizes an ENUM server.
2. Description of Related Art
The recent rapid growth of the Internet has drawn attention to an IP telephone system that enables low-cost voice communications with a telephone apparatus at a remote place as well as free voice communications between IP telephone apparatuses owned by subscribers. Furthermore, there are protocols that associate Internet services or resources on the Internet with telephone numbers, such as “ENUM” (tElephone NUmber Mapping) protocol that is defined by RFC 2916 (Publication 1) and has been studied by IETF (Internet Engineering Task Force) and ITU-T (International Telecommunication Union—Telecommunication Standardization Sector).
“ENUM” protocol is designed to allow retrieval of an IP address or a URI (Uniform Resource Identifier) based upon a telephone number that is converted into the E.164 system defined by ITU-T, utilizing DNS (Domain Name System).
An IP terminal apparatus that performs under ENUM protocol is equipped with not only an IP telephone function but also with a plurality of functions such as facsimile and e-mail functions. In addition, a multifunction apparatus having functions such as printer and scanner functions has been provided.                [Publication 1] Issued by ENUM Trial Japan “ENUM Trial Japan First Report” May, 2004        
However, an IP terminal apparatus called a multifunction apparatus has the following problems when communication is performed between multifunction apparatuses.
When communication is performed between multifunction apparatuses, although it is possible to perform voice communication by selecting from among IP telephone, facsimile and e-mail functions, both IP terminal apparatuses do not necessarily have all of the communication functions installed. Therefore, when a multifunction apparatus user on the transmitting end selects a communication function that is not stored in a multifunction apparatus on the receiving end, communication failure occurs. This requires the user extra work before identifying communication functions that are selectable for the multifunction apparatus on the receiving end.